AN INVESTIGATION OF BONE NECROSIS AND HEALING AFTER CRYOSURGERY, PHENOL CAUTERY OR PACKING WITH BONE-CEMENT OF DEFECTS IN THE DOG FEMUR

A corticocancellous core was removed from the lateral condyle of both femurs in 26 skeletally mature dogs. The cavity was treated with cryos urgery, phenol cautery or packing with bone cement. The animals were k illed after 1, 4, and 12 weeks in the phenol and cement groups, and al so after 24 weeks in the cryosurgery group. The extent of the bone nec rosis and healing was assessed in each group. After cryosurgery the ex tent of necrosis was profound in that the area of damage was 365% comp ared to the area of the cavity; the depth of necrosis extended between 2.5 and 14 mm, beyond the cavity wall. The effect of phenol was negli gible in that only microscopic areas of superficial focal necrosis wer e found around the cavity wall. Bone cement produced an area of necros is of 153% compared with the cavity, with a depth of between 1.3 and 2 .8 mm. Regeneration in the region of necrosis after cryosurgery was on ly scanty by 4 weeks, but by 12 weeks considerable areas of regenerati on were identified and complete healing was observed by 24 weeks. Rege neration of the necrotized bone produced by bone cement packing was ra pid and similar to that of the control specimens. These findings sugge st that cryosurgery could play a significant role as a surgical adjunc t to curettage in locally aggressive benign bone tumours and in some m alignancies. Phenol cautery is not regarded as an adequate treatment a fter curettage of bone tumours. Although the extent of necrosis was re latively small, packing with bone cement is thought to be a useful cho ice in benign cases.